Vapor-mediated wetting and imbibition control on micropatterned surfaces

Abstract

Wetting of micropatterned surfaces is ubiquitous in nature and key to many technological applications like spray cooling, inkjet printing, and semiconductor processing. Overcoming the intrinsic, chemistry- and topography-governed wetting behaviors often requires specific materials which limits applicability. Here, we demonstrate that droplet spreading and wicking on hydrophilic patterns can be controlled by the vapor of a lower-surface-tension liquid. Condensation of the vapor induces Marangoni forces that delay capillary wicking and contract liquid into a droplet on top of the imbibed film. Thereby, macroscopic droplets can be maintained in an apparent partial wetting state, effectively cloaking the pattern. We quantify how pattern characteristics and vapor condensation compete, balancing in different wetting states from pinning to complete imbibition. Since this balance is the result of nonequilibrium processes rather than static wetting phenomena, it can be reversibly tuned by modifying the vapor concentration. This way, we guide droplets across patterns and even extract previously imbibed liquids, devising strategies for coating, cleaning, and drying functional surfaces.